Codex Tasks: start_task_turn returns UNAVAILABLE for an existing readable task #54013

On October 14, 2026, the Codex Tasks connector could list and read an existing task, but a request to continue that same task failed:

• Operation: start_task_turn
• Error: InternalError
• Code: UNAVAILABLE
• Message: Codex Tasks could not complete the request.

A subsequent read showed the previous turn and no new turn from the failed request.

Expected: The requested turn starts, or the connector returns an actionable explanation identifying the unavailable component.

This is the connector-level portion of the same incident documented in #54012, separated for component-level triage at the user's request. It is not a separate reproduced outage. The associated dot task also reported an unavailable execution environment. We have not established whether these errors share a cause, or whether the connector, task routing, or executor was responsible. No successful fresh-task control test or exact current desktop app version was captured.

Please advise which minimal diagnostics can distinguish those possibilities, or consolidate with #54012 if preferable. No private task IDs, content, local paths, account details, or raw logs are included.